Cocoabutter replacement fat compositions

ABSTRACT

Novel fat compositions are provided suitable for use as cocoabutter substitutes, which consist substantially of symmetrical disaturated triglycerides of C 16  and C 18  fatty acids. They may be obtained by interesterification in the presence or absence of the free fatty acids, using a 1,3-selective lipase enzyme catalyst to effect a limited degree of randomization in these positions.

This invention relates to chocolate fats.

Cocoabutter is rich in the three 2-oleyl disaturated C₁₆ and C₁₈ fattyacid triglycerides POP, POSt and StOSt, where P=palmitic, O=oleic, andSt=stearic. These confer the melting properties in particular for whichthe fat is highly prized. The relative proportions of these glyceridesin this and other similar fats, which may be used for providingcocoabutter substitutes, may be represented as points on a ternarytriangular composition diagram. The lines joining the points on thediagram represent the proportions of the glycerides in blends of thefats and form a polygonal figure on the diagram.

The figure is bounded by a curve representing the compositions ofmixtures of the three glycerides in the proportions in which the twosaturated acid residues in the 1- and 3-positions are randomlydistributed among the three. The curve may be derived mathematically andconforms to the equation Z² =4 XY, where X=StOSt, Y=POP and Z=POSt. Theabove points representing natural fats in the diagram, fall on or veryclose to the curve because it happens, as the result of the plantmetabolism involved, that 1,3-random distribution occurs innaturally-occurring vegetable fats between these three glycerides. Thenovel fat compositions lying under the curve outside the polygonalfigure have been found useful in the art. A typical ternary diagramshowing the curve and the principal natural fats lying on it appears inFIG. 1.

According to the present invention therefore novel fats useful forproviding cocoabutter replacement fats in chocolate compositionscomprise 2-oleyl disaturated triglycerides of C₁₆ and C₁₈ fatty acids inthe relative proportions represented on a ternary POP/POSt/StOStcomposition diagram outside the polygonal figure, as hereinafterdefined, bounding natural fats and their blends and under the curve forthe triglycerides in 1,3-random distribution.

The polygonal figure representing known fats and their blends lies belowthe curve for fully 1,3-randomised compositions on which natural fatslie and above the POP/StOSt base line of the ternary diagram. The baseline of the polygon on the diagram is drawn between the natural fatsconsisting most nearly of POP and StOSt respectively. These are palm andshea oils, but since in practice both contain a few percent POSt thebase line of the polygonal figure lies correspondingly above thePOP/StOSt base line of the diagram. The novel compositions of theinvention lie both above and below the base line of the polygonalfigure. Those above it lie within segmental areas cut from the curve bythe other sides of the polygonal figure. Those below it lie in theroughly trapezoidal area between the base lines of the diagram and thefigure.

Novel fat compositions of the invention may be obtained with the aid ofthe selective randomisation method described in our British Pat. No.1,577,933. According to this method the fatty acid residues in1,3-positions of glycerides are randomised selectively, under theinfluence of an appropriate enzyme catalyst, for example Aspergillusniger. The selective randomisation of its glycerides shifts the positionof a fat or fat mixture lying on the diagram below the curve and withinthe boundaries of the polygonal figure, to a point nearer the curveuntil it falls within one or other of the novel areas in accordance withthe invention. At this stage the 1,3-randomisation is still incomplete.It may be effected with or without overall change in fatty acidcomposition of the three principal fatty acids concerned. Therandomisation may also be carried out in the presence of free palmiticor stearic acid to change the overall composition.

If the selective 1,3-randomisation is continued to completion then a fatcomposition is obtained falling on the curve and blending is necessarywith suitable fat to provide a composition falling within one or otherof the segmental areas. In particular, POP, StOSt and/or POSt which maybe obtained by synthesis, can be used for this purpose.

A limited change in the relative proportions of POP/POSt/StOSt in anatural fat may occur on fractionation for the removal of otherglycerides from the fat, but this method is not highly effective.

These novel fats of the invention which appear below the base line ofthe polygonal figure in the diagram may similarly be obtained bydepletion of the POSt content of natural fats and their blends, forexample by the above interesterification method using either palmiticacid or stearic acid as a reactant with the glycerides of the fats.

It has already been proposed in our British Pat. No. 1,431,781 to blenda mid-fraction of palm oil containing substantial amounts of POP withinter alia 1,3-distearyl-2-oleyl glyceride, of at least 85% purity andsuch compositions are excluded from the scope of the present invention.Subject to this exception the novel compositions of the invention may beobtained by use of synthetic triglycerides. However, the inventionextends the area of fat compositions obtainable without synthesis of theseparate 2-oleyl palmityl and stearyl glycerides. The flexibility of fatformulations in the chocolate trade and in others is thereby increased,for example for suppository fats, where triglyceride formulations mustbe adapted to meet specific physical requirements, particularly formelting and solidification characteristics, many combinations of whichhave hitherto appeared difficult to meet. Compositions with similarphysical attributes, particularly relating to desired meltingperformance, may be plotted on the diagram and extrapolated through theareas of the novel compositions of the present invention to predictthose of the novel compositions which have similar characteristics. Forexample, the fats of the invention preferably exhibit a solids content(N value) at 35° C. of about 3% and at 30° C. of about 30% or more,measured by pulse NMR (Fette, Seife und Anstrichmittel, 80, 1978 p.180). These characteristics are exhibited by an area of POP-rich blendsfalling in the polygonal figure, and in areas outside in accordance withthe invention, both above and below the figure. Above it is a segmentextending between the compositions of cocoabutter and palm oil on thecurve. Below it is another area of compositions meeting thesecharacteristics. Another range of compositions in accordance with theinvention substantially satisfies the requirements N₃₅ about 4% andT_(max) ≧28.3° C. Yet another range of fat compositions according to theinvention, falling within areas above and below the figure described,substantially meets the requirements T_(max) ≧29° C. with a minimum riseof 3.5° C., and D₃₅ ≦6%, Many others may be shown on the diagram.

Preferably the compositions of the invention consist substantially ofthe three triglycerides POP/POSt/StOSt but other triglycerides may bepresent, in an amount not exceeding approximately 30% of the totalcomposition, preferably 20% or less. Natural fats containing substantialamounts of these three triglycerides may be concentrated by means suchas fractional crystallisation familiar to those skilled in the art,without disturbing their relative proportions, to produce in practicefats which, while they may not consist entirely of these glycerides, areto all intents and purposes fully randomised in the 1,3-positions. Inparticular, a mid-fraction of palm oil may be obtained consistingsubstantially of the three triglycerides in proportions virtuallyrepresenting complete 1,3-randomisation and the same applies to a sheafraction from which lower melting glycerides have been removed.

EXAMPLE 1

A mixture of a mid-fraction of palm oil with stearic acid wasinteresterified in the weight ratio of 1:0.15, using the methoddescribed in our British Pat. No. 1,577,933 including the use on aCelite support of Aspergillus niger lipase as enzyme catalyst which isselective in its randomisation action, in the 1- and 3-positions only offatty acid glycerides. Randomisation of these positions is demonstrablycompleted from the analysis of the POP/POSt/StOSt of a mid-fraction ofthe crude product which was found to lie precisely on the1:3-randomisation curve of a POP/POSt/StOSt ternary composition diagram.Analysis was by a combination of preparative silver HPLC, details ofwhich appear in J. Chromatography, 188, (1980), pages 205-212, by Smith,Jones and Hammond, and carbon number by GLC analytical methods. Theanalytical data is given in Table 1.

The first of these methods provides an eluent from the chromatographycolumn consisting of a symmetrical disaturated triglyceride fractionwhich is separated in the second method according to carbon number intoa series of three fractions. It is assumed that all the unsaturated acidis C₁₈ and that all the saturated acid present is C₁₆ or C₁₈. A verylimited amount of C₄₈ and C₅₆ is reported in Table 1 and no substantialerror therefore seemed likely in normalising the compositions betweenthe three possible glycerides, from the carbon number analysis using theabove assumptions.

                  TABLE 1                                                         ______________________________________                                                A      B        C        A + C B + C                                          Palm            Product                                                       mid-   Cocoa    mid-                                                          fraction                                                                             butter   fraction 50:50 15:85                                  ______________________________________                                        N values °C.                                                           20        81.6     70.9     88.2   84.3  72.4                                 25        67.7     64.4     78.4   68.7  66.4                                 30        38.6     40.1     48.9   43.1  40.3                                 32        9.7      11.4     14.6   9.5   8.6                                  35        3.0      0.4      8.2    4.8   0.3                                  40        0        0.6      2.0    0.7   0.1                                  Carbon No.                                                                    C.sub.48  2.4      0.5      1.3                                               C.sub.50  74.6     20.3     55.9                                              C.sub.52  17.0     47.1     35.9                                              C.sub.54  5.7      30.4     6.3                                               C.sub.56  0.2      1.4      0.2                                               POP       76.7     20.7     57.0                                              100% POSt 17.5     48.2     36.6                                              StOSt     5.8      31.1     6.4                                               ______________________________________                                    

The mid-fraction of the crude reaction product was obtained afterfiltering-off the supported catalyst and first fractionating at 10° C.from 1.6 times its weight of hexane. After washing twice, each time withhexane at 10° C., the precipitate was extracted twice at 40° C. with 98%aqueous methanol to remove residual free fatty acid and finallyrecrystallised from four times its weight of acetone containing 0.5%water at 5° C.

The mid-fraction recovered was blended first with its own weight of apalm mid-fraction and also with cocoabutter in the weight proportions15:85. The change in solids content with temperature was measured by apulse NMR and the N-values obtained for these compositions according tothe invention are compared in Table 1 with those for the components ofthe blends.

The close comparison shown in Table 1 between palm mid-fraction andcocoabutter and their blends with the enzyme mid-fraction indicates thatsubstantial amounts of the latter may be blended with either fat withoutmaterially affecting their melting characteristics.

EXAMPLE 2

FIG. 2 shows a ternary diagram with compositions marked as below inTable 2 of various novel fat compositions according to the invention andtheir relationship with the 1,3-random distribution curve Z₂ =4 XY. Thefat compositions from which the novel fats were prepared are given inTable 2 and in Table 3 their experimentally-determined POP/POSt/StOStcompositions are listed. These were obtained as in Example 1. Table 4shows the solid contents both of the originating fats and the novel fatcompositions, determined by pulse NMR.

Referring to FIG. 2, the novel compositions of the invention are seen tolie under the curve within the area bounded by the chord to the curvedrawn between the compositions of palm mid-fraction (1) and cocoabutter(2), falling substantially on the curve and representing between themblends of the two fats in various proportions, including blend (3) withequal amounts of these two fats.

                  TABLE 2                                                         ______________________________________                                        Formulation of Fat Blends                                                     Code     Formulations                                                         ______________________________________                                        1        Palm mid-fraction (PMF)                                              2        Cocoabutter                                                          3        Cocoabutter + palm mid-fraction (50:50)                              4        Interesterified cocoabutter/PMF (50:50)                              5        Blend 4 - fractionated                                               6        Blend 5 + Blend 3 (50:50)                                            7        Blend 3 + POSt (96:4)                                                8        Interesterified palm mid-fraction/stearic acid                                   (67:33)                                                           9        Blend 8 + PMF (77:23)                                                10       Shea stearine                                                        11       Shea stearine + POP (70:30)                                          ______________________________________                                    

The novel fats were prepared according to the following methods:

(a) Sample (4)--by incomplete enzymic interesterification of blend (3).This method followed that described in our British Pat. No. 1,577,933,using a continuous method in which the feedstock blend was passedthrough a column containing a packed bed of Celite and the enzymecatalyst. The feedstock consisted of the fat mixture dissolved in apetroleum ether, boiling point 100°-120° C., approximately a kilogrammeof the fat being dissolved in 2.73 liters of the solvent. The feed ratewas adjusted by trial and error to give incomplete interesterification.Further details were as follows:

The column was 1.5 cm in diameter and the packing was in two partsseparated by suitable support means. The lower part consisted of 4 gmsof dried Celite mixed with 3.6 gms of water and was present to ensurethat the feedstock, introduced into the base of the column, wassubstantially saturated with water. The upper bed, which was prepared asdescribed in the above patent specification and was based on 7 gms ofdried Celite with Rhizopus Japonicus, had an activity of 1.1 units/mg.This active packing was wetted with 10% water before packing. Before thepreparation of both parts of the packing, the Celite was adjusted to pH7 by slurrying with dilute hydrochloric acid and dried off.

The feed was supplied at 40° C. and an appropriate feed rate wasestablished for incomplete esterification at between 10 and 20 mls/hour.The product collected over the first 24 hours was discarded to minimisehydrolysis in the final product which was collected over the followingseven days. After solvent removal the product contained 3% free fattyacid.

(b) Sample (5)--by fractionating sample (4). Fat product (4) wasfractionated from a solution of five times its weight in acetone,maintained for an hour at 20° C., the precipitated fat crystals beingwashed once with an equal weight of acetone to yield 5.87% crystals in astearine fraction, which was discarded. The remaining oleine fractionwas again fractionated by holding for an hour at 5° C. in a 10 wt %acetone solution, the precipitate being washed twice with acetone. Thestearine fraction representing novel product (5) was recovered at afractionation yield of 67.4% and was substantially free from uncombinedfatty acid, most of which remained in the oleine fraction.

(c) Sample (8)--prepared generally as described in (a) but in thepresence of free fatty acid, using a packed bed in a column 5 cmsdiameter and containing 540 gms of catalyst comprising enzyme APGmanufactured by Novo on Celite and prepared as described in the aboveBritish patent specification. The enzyme of the catalyst was Aspergillusniger. The column was maintained at 40° C. and the feed supplied to itconsisted of a mixture, dissolved in twice its weight of hexane, of palmmid-fraction with half its weight of stearic acid and water amounting to0.07 wt % of the solution which was supplied to the column at a rate of0.8 kgms/hour. A first fractionation was carried out by holding asolution of the product in 1.6 times its weight of hexane at 8° C., thecrystals being washed once with hexane. A yield of 62% oleine wasrecovered which was extracted at 40° C. in a separatory funnel withmethanol containing 2% water to remake free fatty acid, the amount ofthis extracting solvent being four times the weight of recovered oleine.The separated oil phase was again fractionated from a solution in fourtimes its weight of acetone which was maintained for an hour at 5° C.,the precipitate being washed twice with acetone.

A yield of 68% stearine fraction was recovered, giving an overall yieldof 30% approximately.

The fractionated fat was finally eluted in a 10% solution in a mixtureof equal parts of diethyl ether and hexane, through a column packed withsilica gel in an amount approximately ten times the weight of fattreated. The silica gel was 60 to 120 mesh. An overall yield of product(8) was obtained of 24.2%.

(d) Samples (6) and (9)--by blending. Reference should be made to Table2.

(e) Samples (7) and (11)--by addition of synthetic triglycerides tofats. Sample (11) is of particular interest, being outside the polygonalfigure above described, but containing less POSt rather than more, incomparison with blends represented by the sides of the polygon.

The solids content data in Table 4 indicates that, with the exception ofthe unfractionated product (4), all the novel products of the inventionare useful confectionery fats.

    __________________________________________________________________________                          Carbon Number Analysis of the                                                 SOS triacyl glycerols prepared                                                                Normalised POP/POSt/StOSt                                     by preparative silver phase                                                                   composition of the SOS                                        HPLC            triacyl glycerols                       Fat/Blends            C48                                                                              C50 C52                                                                              C54                                                                              C56                                                                              POP  POSt                                                                              StOSt                          __________________________________________________________________________    1 Palm mid fraction   2.3                                                                              77.2                                                                              17.3                                                                             2.8                                                                              0.2                                                                              79.4 17.7                                                                              2.9                            2 Cocoa butter        0.3                                                                              20.4                                                                              46.9                                                                             30.5                                                                             1.6                                                                              20.9 47.9                                                                              31.2                           3 Cocoa butter + PMF (50:50)                                                                        1.2                                                                              48.4                                                                              32.4                                                                             16.9                                                                             1.0                                                                              49.5 33.2                                                                              17.3                           4 Interesterified Cocoa butter/PMF (50:50)                                                          1.3                                                                              45.4                                                                              40.1                                                                             12.2                                                                             0.8                                                                              46.5 41.1                                                                              12.4                           5 Interesterified Cocoa butter/PMF (50:50)                                      Fractionated        0  45.0                                                                              38.7                                                                             15.1                                                                             0.9                                                                              45.6 39.1                                                                              15.3                           6 Blend 5 + Blend 3 (50:50)                                                                         1.0                                                                              46.1                                                                              36.4                                                                             15.4                                                                             0.9                                                                              47.1 37.2                                                                              15.7                           7 Blend 3 + POSt (96:4)                                                                             0.7                                                                              43.1                                                                              34.9                                                                             15.8                                                                             0.84                                                                             46.0 37.2                                                                              16.8                           8 Interesterified PMF/Stearic acid (67:33)                                                          0.7                                                                              33.4                                                                              47.0                                                                             18.1                                                                             0.6                                                                              33.9 47.7                                                                              18.4                           9 Blend 8 + PMF (77:23)                                                                             0.7                                                                              44.1                                                                              40.6                                                                             14.0                                                                             0.5                                                                              44.7 41.1                                                                              14.2                           10                                                                              Shea stearine       0.4                                                                              4.2 8.6                                                                              81.8                                                                             4.5                                                                              4.4  9.1 86.5                           11                                                                              Shea stearine + POP (70:30)                                                                       0.1                                                                              74.6                                                                              2.9                                                                              21.0                                                                             1.1                                                                              75.7 3.0 21.3                           __________________________________________________________________________

    ______________________________________                                        PULSE NMR SOLIDS CONTENT                                                                   Temperature °C.                                           Fat/Blend      20     25     30   32.5 35   40                                ______________________________________                                        1   Palm mid fraction                                                                            86.6   75.7 47.1 16.8 3.3  0.2                             2   Cocoa butter   74.8   68.2 41.6 13.9 1.1  0.0                             3   Cocoa butter +                                                                PMF (50:50)    71.4   56.7 15.8 2.3  0.5  0.0                             4   Interesterified cocoa                                                         butter/PMF (50:50)                                                                           32.6   23.6 10.5 6.4  1.7  1.1                             5   Interesterified cocoa                                                         butter/PMF (50:50)                                                                           73.0   59.3 7.7  0.0  0.0  0.0                                 Fractionated                                                              6   Blend 5 +                                                                     Blend 3 (50:50)                                                                              69.3   56.2 11.0 1.4  0.1  0.0                             7   Blend 3 +                                                                     POSt (96:4)    70.9   56.8 15.7 2.7  0.5  0.3                             8   Interesterified                                                               PMF/Stearic    81.2   70.0 34.7 11.3 5.4  0.4                                 acid (67:33)                                                              9   Blend 8 +                                                                     PMF (77:23)    76.0   62.2 19.8 7.6  3.3  0.0                             10  Shea stearine  78.8   75.0 65.2 51.3 13.0 2.4                             11  Shea stearine +                                                               POP (70:30)    87.6   82.9 51.8 7.8  0.6  0.8                             ______________________________________                                    

What is claimed is:
 1. Cocoabutter replacement fat compositionconsisting essentially of a ternary triglyceride mixture of POP, POStand StOSt represented on a ternary X/Y/Z composition diagram asexemplified in FIG. 1 under the curve Z² =4 XY, where X=StOSt, Y=POP andZ=POSt, outside a polygonal figure bounding the composition of POP, POStand StOSt in natural fats and their blends on the diagram as exemplifiedin FIG.
 1. 2. Composition according to claim 1 lying within a segment ofthe said curve.
 3. Composition according to claim 2 wherein the saidsegment is bounded on the curve by a chord extending substantially fromthe composition on the curve of cocoabutter to that of palm oil. 4.Composition according to claim 1 lying on the ternary diagram below achord of the curve extending substantially from the composition of sheafat to that of palm oil.
 5. Composition according to claim 1 selectedfrom the group consisting of synthetic StOSt, POSt, POP, their mixtureswith each other and with natural fats and their fractions. 6.Composition according to claim 1, at least part of which comprises a1,3-selectively randomised fat.
 7. Composition according to claim 6comprising a fat incompletely randomised selectively in the 1- and3-positions.
 8. Composition according to claim 1 comprising up to 20%other triglycerides, balance POP, POSt and/or StOSt.
 9. Compositionaccording to claim 1 which contains palm mid-fraction or shea fat. 10.Composition according to claim 1 having a solids content at 35° C. ofabout 3% and at 30° C. of at least 30%.
 11. Composition according toclaim 1 having a solids content at 35° C. of about 4% and T_(max) atleast 28.3° C.
 12. Composition according to claim 1 having a T_(max) ofat least 29° C. with a minimum rise of 3.5° C. and N₃₅ of at most 6%.13. Novel fats having a composition as shown by points (4), (5), (6),(8) and (11) on FIG. 2 of the accompanying drawings.
 14. Composition asclaimed in claim 1 in a blend with cocoabutter.
 15. Method of preparinga composition as claimed in claim 1, wherein a fat comprisingsymmetrical disaturated triglycerides of C₁₆ and C₁₈ fatty acids issubjected to selective randomisation in the 1- and 3-positions in thepresence of a lipase enzyme catalyst and a small amount of watereffective to activate the catalyst.
 16. Process according to claim 15,wherein the selective randomisation is discontinued before completion.17. Process according to claim 15, wherein the randomised fat is blendedwith a natural fat.
 18. Process according to claim 15, wherein therandomised fat is blended with synthetic POP, POSt, and/or StOSt. 19.Continuous process according to claim 15, wherein a stream of the fat insolution is directed over a fixed bed of selective enzyme catalyst andthe randomised fat is recovered from the effluent by removal of the saidsolvent.
 20. Process according to claim 19, wherein the extent ofselective 1,3-randomisation of the fat is limited by adjusting the rateof flow of the stream.